The present invention is an improvement over the automatic tape threading apparatus disclosed and claimed in copending application Ser. No. 164,733, filed concurrently herewith and assigned to the assignee of the present invention. In this copending application, an automatic threading apparatus is disclosed which comprises basically a coupling device and a mechanism for moving the coupling device over a predetermined nonlinear tape path extending between the tape supply reel and the take-up reel of a magnetic tape transport. The function of the coupling device is to selectively engage a leader block which is permanently attached to the end of the tape wound on the supply reel that is disposed in a generally rectangular cartridge.
The take-up reel of the disclosed tape transport is provided with a radially disposed leader block receiving slot which receives the leader block and positions the tape attached to it in a pre-wrap relationship with the hub of the take-up reel. The leader block and the hub are, thus, rotated together during a tape winding and unwinding operation. The coupling device is designed so as to remain coupled to the leader block during the winding and unwinding operation and also to remain attached to the mechanism which has moved it from the position adjacent to the supply reel to the position associated with the take-up reel. As described in the copending application, the coupling device includes a pin disposed with its axis parallel to the axis of rotation of the supply and take-up reels. The pin engages the leader block in a manner which permits the pin to be disposed coaxially with the axis of the take-up reel when the leader block is positioned in the radially extending slot of the take-up reel. The engagement of the pin and leader block is such that the leader block is free to rotate about the pin during the winding and unwinding process. Alternately, the pin could be coupled to the leader block in a manner to cause the pin to rotate on its axis with the leader block by providing suitable bearing elements in the coupling device. In the embodiment of the invention shown in the copending application, the coupling device is permanently attached to a band member which engages a plurality of pulleys, one of which is driven by a suitable motor. The placement of the axis of rotation of the pulleys and their respective diameters are selected to cause a segment of the band to coincide with the tape path over which the tape normally passes from the supply reel to the take-up reel. Rotation of the driven pulley causes movement of the band, the coupling device, the leader block and attached tape through the tape path, and results in automatic threading of the tape.
It has been found that as the tape path becomes more complex in the sense that it involves compound curves with relatively small radii, the pulley-band guiding arrangement becomes somewhat unwieldy and often imposes constraints on the tape path which provides for less than optimum tape transport performance.
The present invention is directed to a relatively simple mechanism for moving the coupling device between the supply reel and the take-up reel which can accommodate rather complex tape paths. The mechanism comprises a continuous channel shaped member, one section of which is formed to coincide approximately with the tape path, and the remaining section of the channel merely being returned to the beginning of the section by some convenient path. A continuous band is disposed in the channel for sliding engagement therewith, and suitable means are provided to drive the band in a forward and reverse direction. Means are also provided for attaching the coupling device to the band whereby the movement of the coupling device moves the leader block over the complex path defined by the channel and threads the tape to the take-up reel.
It is, therefore, an object of the present invention to provide an improved automatic tape threading mechanism.
Another object of the present invention is to provide an improved automatic tape threading mechanism for use with a magnetic tape transport in which the tape path can have various degrees of complexity.
A still further object of the present invention is to provide a relatively simple and inexpensive mechanism for moving a leader block coupling device of an automatic threading apparatus through a complex tape threading path.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention as illustrated in the accompanying drawings.